Presses for drawing sheet metal



Sept. 15, 19311. c. .1. RHODES I I PRESS FOR DRAWING SHEET METAL Filed oct. 29, '1929 zPatented Sept. 15:, 1931 UNITED STATES mais CHARLES JOSEPH RHODES, OF WKEFIELD, ENGLAND PRESSES FOR DRAWING SHEET METAL Application filed October 29, 1929, Serial No. 403,186, and in Great Britain December 17, 1928.

This invention relates to presses for drawing sheet metal, and it has for its object certain improvements in or modifications of presses of the type described in specification For presses of the kind referred to it is found that there is a tendency when drawing bodies having a flanged end in which the flange is comparatively wide for the metal 1o to become stressed and tear or crack, this tendency being due to the larger surface of Contact between the blank and the upper die and draw-ring.

In the press referred to it has been usual to arrange the levers operating the movable forming block or plug in a manner such that there is a substantially even pressure exerted over the whole of the blank. it has been found that by suitably varying` this pressure the aforesaid objections are avoided. To

this end, in accordance with 4the present invention, instead of arranging the pivots for the levers operating the plug in a manner such that they are equidistant or substantially equidistant from the points of connection of the said levers to the rod actuating the plug and to the rods by which said levers are suspended from the table supporting the draw-ring, said levers are so arranged that the pressure exerted by the moving plug is greater than that applied by the draw-ring and top die, such variation in pressure being designed to compensate for the increased area, and consequently increased friction surface presented by the flange.

Preferably provision is made whereby thev pivotal point of the levers may be readily altered so that variations of the leverage ratios of the ends of the said levers may be readily secured. Thus, for example, the levers may each be slotted longitudinally, the pivots or a body carrying them being slidable in said slot, provision being made for ret-aining them in their adjusted positions. Again the faces of the levers adjacent the slots may be serrated or roughened, bodies Carrying the pivots of said levers being provided having surfaces provided with similar serrations or roughening to engage those upon the lever. By closely spacing said serrations not only may a very nice adjustment be secured, but accidentalmovement of the bodies longitudinally of the levers is prevented. Suitable provision would be made for maintaining the engagement of the serrated or roughened surfaces one with another.

1n order that the invention may be the better understood drawings are appended in which:

Fig. 1 is a sectional View showing a form of the invention.

Fig. 2 is a side view.

Fig. 3 is a perspective view in which is incorporated the present invention.

In the appended drawings 1 indicates the table of the press and to which table, supported by the frame of the press which is not shown, is secured a plate 3 carrying the lower die 4. 5 indicates the upper die, and l 6 indicates a pressure or draw-ring resting,

plate 11 is secured to the rod 9 by means ofV i a screw thread formed thereon, and engaging a similar thread formed in plate 11, a lock nut 13 being provided.

Encircling the tubular rod 9 is a helical spring, the upper end of which bears against the underside of the table 2, whilst the lower end engages the upper surface of a nut 14: uponthe rod 9, and by means of which nut the initial degree of compression of the spring may be adjusted.

15 indicates levers each pivotally mounted at 152L upon each of the downwardly depending lugs 12 of plate 11, and each provided at its inner end with a toothed sector 16 engaging a rack 17. Each rack 17 is formed integral with or secured to a spindle`18 passing through the aforesaid tubular rod 9, the upper end of said rod being connected to the movable forming plug 19 in the lower die 4.

In order to permit of variation in the leverage ratios, the levers 15 are each provided with a series of perforations indicated by 20. 2l indicates links by which the levers are supported from the even pressure table, said links being connected to the levers by pins 22 which are removable, and for which purpose may be retained against longitudinal movement by means of split pins23, or other readily removable devices. As the links are pivotally connected to the even pressure table, their ends may be readily swung inwards or outwards to bring. their. ends. into register with the holes in the levers 15.

Claims:

l. In combination with .a press table, a lower die, a pressure table, a pair of" links pivoted to each end of said pressure table, a tubular member havingva collar at its top, said -press table having a `.recess of adepth to receive the whole of said lcollar with its upper face flush with tthe upper ace of said table, said tubular member being externally threaded at its lower end; a fixed platemember threaded and supported on `said tubular member and having integral downwardlydirented perforated lugs; a spindle secured to said lower die and extending through and below said tubular member, a gear rack on the end of said spindle, ameohanical buier interposed between theV pressure table and said plate-member, coggedlevers `engaging said gear rack and pivoted to the `lugsof said fixed plate, said. levers .each being Yprovided with a series of holes, providing means for pivotal attachment to the lower ends of said links for obtaining variations in the leverage ratio of the apparat-us.

2. In combination with al press table, ya lower die, a tubular member supported 'by the press table, a spindle supportedbythe lower die, a pressure table having adepressed seat and movable on said tubularmember, a plate fixed on the tubular member andhaving perforated lugs, a mechanical( vbulier disposed between they said plate and 'the pressure table with its upper .end resting insaiddepressed seat, a gear rack on said spindle, cogged ypivoted levers engaging said gear rack and :each having a series of holes, anda pair of links pivoted to each end of said-.pressure plate, and to said levers whereby a determined leverage 4ratio may be obtained.

In testimony whereof I have lhereunto set my hand.

CHARLES JOSEPHy RHODES. 

